<转载>Vray抗锯齿详解

Here is an example briefly demonstrating the effect of different antialiasing filters on the final result.

Note that rendering with a paricular filter is not the same as rendering without a filter and then blurring the image in a post-processing program like Adobe Photoshop. Filters are applied on a sub-pixel level, over the individual sub-pixel samples. Therefore, applying the filter at render time produces a much more accurate and subtle result than applying it as a post effect. V-Ray can use all standard 3ds Max filters (with the exception of the Plate match filter) and produces similar results to the scanline renderer.

The Adaptive image sampler was used for the images below, with Min/Max rate of -1/3 and the Rand optionon.

Filter

Image

Zoomed-in image

Comments

Filtering is off

Applies an internal 1x1 pixel box filter

Area filter, size 1.5 (default setting)

Slightly blurrs the image, visually more pleasing than the box filter.

Area filter, size 4.0

More blurring

Blend filter

Combination of a sharp and a soft filter, kind of dreamy effect

Catmull-Rom

Edge-enhancing filter, often used for architectural visualizations. Note that edge enhancing can produce "moire" effects on detailed geometry.

Note that moire effects are not necessarily a result of poor image sampling. In general, moire effects appear simply because the image is discretized into square pixels. As such, they are inherent to digital images. The effect can be reduced through the usage of different antialiasing filters, but is not completely avoidable.

The scene is very simple: a sphere with a very fine checker map applied, texture filtering is off. The images were rendered with a very high sampling rate (15 subdivs, or 225 rays/pixel). This is enough to produce quite an accurate approximation to the pixel values. Note that the image looks quite different depending on the filter: